Evaluation of Pump Performance of a Percutaneous-Type Pulsatile Left Ventricular Assist Device (MAD Type 5 and Type 6)

We have been developing a percutaneous-type left ventricular assist device named the Modified Assist Device (MAD). The system is composed of an air-driven sac-type blood pump and cannula in which an inflow and an outflow valve have been installed. With the MAD type 5, a maximum pump flow of 2.51/min was obtained in a mock circulation study. For clinical application of this ventricular assist device, a new model, MAD type 6, was developed and was evaluated in in vitro and in vivo experiments. To obtain satisfactory anatomical fit and durability, a spiral was installed in the cannula of MAD type 6. In in vitro evaluation, the pressure gradients across the inflow and outflow valves were 110 mmHg and 75 mmHg at a flow rate of 21/ min. With the MAD type 6, the index of hemolysis was almost the same as that of a centrifugal pump. The durability test was maintained for more than 30 days without deterioration of the new system. In an animal experiment, using dogs, more effective systolic unloading and diastolic augmentation were observed by the activation of the MAD type 6 than with an intra-aortic balloon pump (IABP) assist. As for the peripheral circulation, the MAD type 6 device produced greater carotid artery flow than did the the IABP assist. In conclusion, the MAD type 6, a pulsatile-flow device, appears to have a design and function suitable for clinical application.